I Am 12 Weeks Pregnant And I Went For The

I am 12 weeks pregnant and i went for the ultrasound where they tell you if your baby hs risk of birth defects. Doctor said there was no risk everything looked fine and baby's heartbeat was 150 but he did tell me the protein in my placenta was a little low like i think normal was 4.0 and mine was 3.8 should I be worried !? What can this cause!? How can I fix this !?